River Keepers Handbook: A Guide to Protecting Rivers and Catchments in Southern Africa, by Lori Pottinger, International Rivers Network, Berkeley, 1999."/>
Following is an excerpt from River Keepers Handbook: A Guide to Protecting Rivers and Catchments in Southern Africa, by Lori Pottinger, International Rivers Network, Berkeley, 1999.
The development of water and power supply have mostly followed the traditional engineering and supply approach – in other words, building large dams and power plants. Alternatives were seldom considered. In fact, such alternatives used to be discounted as experimental concepts that couldn’t meet the demands of the "real world".; But in the past decade or so, alternatives to traditional water and energy supply approaches have proved themselves in real–world applications around the globe. The following section describes the many alternatives now being practiced in energy and water supply which can help human society flourish without undermining the integrity of the ecological systems we depend on.
Conservation and Demand Management
Conservation can save a huge amount of water and power before it is even used – and money, too, since it prevents the need for building expensive large–scale projects. An entire field of expertise that focuses on conservation and efficiency measures, called "demand management", has arisen to develop effective ways to conserve both power and water. Demand management treats the volume and pattern of water– or power–consumption as variable, and aims to change the behaviour of consumers either voluntarily (prices, education) or involuntarily (regulations, policies). Demand management has many benefits to society besides reducing wasteful use of water and power. Such measures can reduce pollution and environmental damage, create more jobs than building new water and power plants would, save money (and thus free up funds to help bring water or power to the poor), and pose less economic, environmental and social risk to society than large–scale infrastructure projects.
It seems logical that securing "new" supplies of water and power through the conservation of existing resources should always be considered first. Yet only recently has this approach drawn much official interest in the region. Civil society can play a major role in pressing to ensure that demand management is explored first when water or power needs increase, and that it is given a full analysis as a legitimate alternative. Too often, such measures have been seen as a way to merely supplement the output of large development schemes rather than replace them.
Demand–management plans may include a number of tactics, including the following:
Energy efficiency measures can reduce pollution and greenhouse gas emissions, save money and create jobs. They also pose significantly less risk for society than large–scale power plants. For example, what happens if the government has committed to build a large–scale power plant in anticipation of future needs and then the economy suffers a serious downturn? Most supply–side investments require long–term commitments, so someone is going to pay for that unneeded power plant for some time to come, whether it is needed or not. In contrast, demand management efforts are much more flexible, and can be ramped up and down as needed, tracking the economy’s ups and downs. For example, energy–efficient building standards will provide lots of energy savings when the economy is booming and the energy savings are needed the most (because more people are using more energy), and much lower savings when the economy is stagnant and energy savings are less important.
The potential for saving money by saving electricity is enormous. Electricity costs the world more than $500 billion annually, according to the US–based efficiency research group the Rocky Mountain Institute. Energy experts believe that energy efficiency measures could save 30–50 percent or more (and even greater in developing countries that are still using old, inefficient technologies).
Efficiency measures are not free, but they are very cheap compared to new power supply – and bring other economic benefits besides lower costs. Utilities report that the average cost of implementing electricity savings of all kinds has been 2 cents per kilowatt–hour (kWh), and the best–designed programmes are many times cheaper than that. In contrast, each kWh generated by an existing power plant costs upwards of 5 cents (and as high as 20 cents), and that does not include the cost of repairing the environmental impacts of energy plants. Numerous studies have shown that undertaking efficiency measures also brings more jobs than building new power plants. It takes many more energy auditors to go through one million buildings, make recommendations, add insulation, install efficient lighting, etc. than it takes construction workers to build the power plants necessary to provide energy to the same one million buildings.
In some countries (especially those using the most energy), demand management has advanced significantly. For example, since 1973, the United States has gotten more than four times as much new energy from demand management savings as from all expansions of domestic energy supplies put together, according to the Rocky Mountain Institute. The energy savings already achieved have cut Americans’ energy bills by more than $200 billion a year, compared to what they would collectively be spending if they used energy at the same rate as in 1973.
Although it may seem hard to believe, the opportunity for energy savings in developing countries is very high, despite their overall low per–capita use of energy. One reason is because older equipment is not replaced or maintained as often as in richer nations, meaning that already–inefficient machinery is operating even more inefficiently than when it was first purchased. Developing countries have also become "dumping grounds" for inefficient appliances or technologies that are no longer allowed in developed countries. It may seem logical for poor countries to buy, say, cheap air conditioners that do not meet US efficiency standards and therefore can no longer be sold there, but those same cheap air conditioners will require more power plants to run them – and more money out of consumers’ pockets every time they are used. Finally, since most developing nation governments have been most concerned about bringing services to unserved citizens, they have been slower to develop standards and policies to increase efficiency. Therefore, new buildings and locally manufactured equipment may be very inefficient.
The Importance of the Right Regulatory Framework
Demand management efforts have been most effective when governments have required utilities to periodically submit long–term plans for meeting consumer demand in the cheapest way possible (usually this is part of an integrated resource planning process). This requires them to look at demand management as well as supply–side options. Although a utility’s assumptions may not always be a fair assessment of what is really possible with efficiency measures, the process is open to public debate, thus NGOs have some leverage in influencing the process.
Another unique lesson about demand management is now being learned in the US, which is in the process of deregulating its energy markets to open the field up to competition. As this process gains wider footing, many states that are deregulating their energy market are moving in the direction of taking responsibility for demand management away from utilities and placing it in a newly formed, government–run (or government–overseen) "efficiency utility".; The argument is that, despite regulators’ best efforts to give them the right incentives, most utilities continue to perceive themselves as having conflicting interests: they have to do demand management on the one hand but sell electricity on the other. California, New York and others have placed a tax on all electricity sales to collect a pool of money that will be spent on demand management programmes. A state agency will use this money to hire firms to implement demand management programmes with this money.
Some Ways to Save Energy
There are many, many ways to capture energy through efficiency improvements, with new innovations coming out all the time. The following describes some of the most common and best efficiency measures.
Lighting: Great progress has been made in making lighting more energy efficient. Traditional incandescent light bulbs use 90 percent of their energy to produce enough heat to glow, compared to compact fluorescent light bulbs, which are four times more efficient and last 9–13 times longer. In Japan, 80 percent of homes are lit by compact fluorescent bulbs. Making use of natural daylight through windows is also an effective way to save energy (and costs to the consumer) from lighting. According to the Rocky Mountain Institute, a 1x1.6 metre window in direct summer sun lets in more light than a hundred 60–watt light bulbs.
Home appliances: Over the past three decades many developed countries have greatly reduced their energy consumption because of improvements to appliances. Household appliances such as furnaces, water heaters and cooking ranges have cut their electricity use by an average of 50 percent. Appliances such as refrigerators, electric water heaters and stoves have the potential of becoming 3–6 times more efficient (and in sunny climates, solar water heaters can reduce a home’s energy use even further). When older appliances are being replaced, it is good to prioritize to get the most energy savings: air conditioners are the single biggest energy user in a home, followed by refrigerators.
Buildings: Houses and apartment buildings can be made more efficient (for both heating and cooling) by increasing insulation levels in the walls and roof, improving the energy–efficiency of the windows and, for hot climates, planting shade trees near the building. Windows bring light and warmth into buildings, but can also be a major sources of heat loss in the winter and heat gain in the summer. However, modern energy–efficient windows can help minimize a home’s heating, cooling, and lighting costs by 35–45 percent, according to some estimates. The factors which affect the energy efficiency of a window are the type of glazing material (e.g., glass, plastic, treated glass); the number of layers of glass; the size of the air space between the layers; the heat conductance of the frame materials, and the "tightness" of the installation.
Shade trees reduce solar heat gain by absorbing heat from the sun before it can reach the building, as well as cooling the surrounding air through evapotranspiration. Air conditioning savings from landscaping range from 25–60% over the course of the summer, depending on building type, amount of insulation, landscape design and climate. Some utilities in hot climates have sponsored tree–planting programmes. For example, The Sacramento Municipal Utility District (SMUD) in California is operating one of the US’s most ambitious tree planting programme. SMUD plans to plant 500,000 trees by the year 2000 through its Shade Tree Programme, and had planted more than 160,000 trees by 1995, mostly in residential areas of the city. The utility funds the programme, which is implemented by the non–profit Sacramento Tree Foundation. Fast–growing deciduous trees are a good choice, as they allow sun in in winter.
Commercial, Institutional and Industrial
Technologies and Appliances: Improving efficiency in industrial settings almost always includes improved basic production technologies – especially motors, which use up to two–thirds of industrial electricity in most countries, according to the Stockholm Environment Institute. The science of energy efficient motors is complex, and often specific to the industry application. In the steel industry, which uses a considerable share of energy in many countries, advanced technology furnaces can result in 40–45 percent energy savings. Similarly, it has been estimated that aluminum production can be 50 percent more efficient through the use of improved equipment, and even further through the use of aluminum recycling (secondary use of aluminum requires just 4 percent of the energy needed to produce it the first time). For some industries – such as supermarkets, restaurants and hospitals – refrigeration is an area where big savings can be found.
Buildings: Although there are some similarities in efficiency measures for residential and commercial buildings, the best ways to make commercial buildings more efficient are through improvements to air conditioning and lighting systems.
WATER CONSERVATION TECHNIQUES
Using water more efficiently can, in effect, create a new source of supply. According to Sandra Postel, an expert in international water scarcity problems, technologies and methods are now available which could cut water demand between 40 and 90 percent in industry, 30 percent or more in cities, and between 10 and 50 percent in agriculture without reducing economic output or quality of life. In developing countries, the potential benefits of water demand–side management programmes are huge in terms of money saved and ecological damage avoided, as well as freeing up water supply to extend coverage to the unserved.
Water management expert S. Mtetwa of Zimbabwe described the goals of demand management programmes for water at a 1998 United Nations conference on freshwater management in Zimbabwe:
"Water demand management aims to:
Demand management includes several approaches to conserve water, including economic policies, notably water pricing; laws and regulations, such as restrictions on certain types of water use; public and community participation, to ensure that solutions are workable and have public support, and technical solutions, such as installing water flow restrictors. Reducing the amount of water consumed is key to cutting both water and energy expenses. Demand management cannot be thought of only from a technical angle. Water–saving technical measures always have economic, legal, institutional and political aspects that must be considered as well.
Below is a checklist of specific ways to cut demand. Most are designed for use by local or regional water suppliers or government agencies. Citizens should press to ensure their water utilities and governments are doing as many of these things as possible.
To reduce water wastage nationally or regionally:
Industrial Water Conservation
Industry is, generally speaking, water–intensive. According to South Africa’s Department of Water Affairs, a factory can use 450,000 litres of water to produce a small car, 130 litres to produce a bicycle, and 53 litres to make a pair of shoes. Coal mining in Mozambique has been estimated to use up to 1 cubic meter per second in the mining and washing process. Although water use for the industrial sector is relatively low in Africa (for example, it is under 8% in South Africa), there is still much room for improvement. In some parts of the world, certain water–intensive industries have greatly reduced the amount of water needed for production, including chemicals, iron and steel, and paper. In some countries these industries are both reusing and recycling water in current production processes and redesigning production to require less water. For example, in the US, industrial water use dropped by over one–third between 1950 and 1990, while industrial output nearly quadrupled. In the former West Germany the total amount of water used in industry today is the same as in 1975, while industrial output has risen by nearly 45 percent. In Sweden, strict pollution–control measures have cut water use in half in the pulp and paper industry, while production has doubled in little more than a decade.
Progress has been slow in developing countries, however. In China, for instance, the amount of water needed to produce a ton of steel ranges from 23 to 56 cubic metres, whereas in the US, Japan and Germany, the average is less than 6 cubic metres. Similarly, a ton of paper produced in China requires around 450 cubic metres of water, twice as much as used in European countries. China now faces severe, chronic water shortages in many of its largest watersheds. China’s Yellow River, one of its largest rivers, is now considered to be ephemeral because it is so over–allocated. China also has more than 100 cities that are sinking dangerously due to excessive extraction of groundwater.
Modified Agricultural Practices
Since agriculture accounts for nearly 70 percent of the world’s fresh water withdrawn from rivers, lakes, and underground aquifers for human use, the greatest potential for conservation lies with increasing irrigation efficiency. By reducing irrigation by 10 percent, we could double the amount available for domestic water worldwide. This can be done by converting to water–conserving irrigation systems; taking the poorest and steepest lands out of production; switching to less–thirsty crops (which may require changes to government subsidies for certain crops); implementing proper agricultural land drainage and soil management practices, and reducing fertilizer and pesticide use.
Typically, governments provide water to large commercial farmers at greatly subsidized rates, decreasing the need for conservation and promoting wasteful practices. This has led to widespread use of wasteful irrigation systems. Studies show that just 35–50 percent of water withdrawn for irrigated agriculture actually reaches the crops. Most soaks into the ground through unlined canals, leaks out of pipes, or evaporates before reaching fields. Although some of the water lost in inefficient irrigation systems returns to streams or aquifers where it can be tapped again, water quality is invariably degraded by pesticides, fertilizers and salts. This is in fact another way that commercial agriculture "uses" water: by polluting it so that it is no longer safe to drink. In areas where commercial agriculture is prevalent, runoff from farms has poisoned water supply with dangerous levels of toxics.
Poorly planned and poorly built irrigation systems not only harm water quality, but can also irreparably harm the crop–growing capability of the land through salinization. Especially in arid areas, salts that occur naturally accumulate in irrigated soils. Poorly drained irrigation water can pollute water supply, and raise the groundwater table until it reaches the root zone, waterlogging and drowning crops. Globally, some 80 million hectares of farmland have been degraded by a combination of salinization and waterlogging.
Switching to conserving irrigation systems has the biggest potential to save water used for agriculture (experts say drip irrigation could potentially save 40–60 percent of water now used for agriculture). The most common water–conserving irrigation systems are some form of drip irrigation (also called micro–irrigation). Conventional sprinklers spray water over crops, not only irrigating more land than is needed to grow the crop but also losing much to evaporation. Drip irrigation, however, supplies water directly to the crop’s root system in small doses, where it can be used by the plant’s roots. Water is delivered through emitters that drip water at each plant, or perforated piping, installed on the surface or below ground. This keeps evaporation losses low, at an efficiency rate of 95 percent.
Although by 1991 some 1.6 million hectares were using drip irrigation worldwide, this is still less than one percent of all irrigated land worldwide. Some countries have made drip irrigation a serious national priority, such as Israel, which uses drip irrigation on 50 percent of its total irrigated area. But clearly it is the exception, and most dry countries have a long way to go.
Another promising irrigation system, called low–energy precision application (LEPA), offers substantial improvements over conventional spray sprinkler systems. The LEPA method delivers water to the crops from drop tubes that extend from the sprinkler’s arm. When applied together with appropriate water–saving farming techniques, this method also can achieve efficiencies as high as 95 percent, according to the report Solutions for a Water–Short World, published by the Johns Hopkins Population Information Programme (US). Since this method operates at low pressure, energy costs also drop by 20 to 50 percent compared with conventional systems. Farmers in the US state of Texas who have retrofitted conventional sprinkler systems with LEPA have reported that their yields have increased by as much as 20 percent and that their investment costs have been recouped within one or two years, the report states.
Another growing practice is to reuse urban wastewater on nearby farms growing vegetables and fruits. Today, at least half a million hectares in 15 countries are being irrigated with treated urban wastewater, often referred to as "brown water".; Israel has the most ambitious brown–water programme of any country. Most of Israel’s sewage is purified and reused to irrigate 20,000 hectares of farm land. One–third of the vegetables grown in Asmara, Eritrea, are irrigated with treated urban wastewater. In Lusaka, Zambia, one of the city’s biggest informal settlements irrigates its vegetable crops with sewage water from nearby settling ponds.
Traditional Water Harvesting
Southern Africa has a rich tradition in small–holder farming. Water consumption in such systems is usually sustainable. Such systems may include rain– and groundwater harvesting, micro–dams, shallow wells, low–cost pumps, and moisture–conserving agricultural practices. Careful consideration of traditional water–saving techniques combined with effective modern methods may help to balance the needs of dryland agriculture and help to meet the developing world’s water demand.
Up until recently, many of these traditional irrigation methods were excluded from official irrigation programmes in Southern Africa, such as UN Food and Agricultural programmes. According to water expert Sandra Postel, although they are now getting greater recognition, Africa’s small–scale irrigation methods are rarely offered the investment credits, extension services and other forms of support given to large public irrigation schemes.
Runoff agriculture has been used in regions where the average yearly rainfall is 100mm or less. During high rainfall, rainwater is collected and diverted into storage tanks and used throughout the dry season.
The Sonjo of Tanzania divert water with small brushwood dams, up to three metres high, to irrigate the slopes of Mount Kilimanjaro. Small dams of this type are easily destroyed by floods, a feature which can enhance the sustainability of the overall system as the floods then wash away most of the sediments behind the dams. Unlike large dams, brushwood dams still permit water to flow through, thereby decreasing ecological damage downstream. Because the dams are built with local materials and labour, rebuilding them is usually not a major expense.
Another traditional method involves placing long lines of stones along the contours of gently sloping ground to slow runoff and spread the water across a wider area. This practice has increased crop production by about 50 percent, according to Solutions for a Water–Short World.
Dambo farming in Zimbabwe is a classic example of the sustainable uses of a natural water resource. Dambos are small (usually less than half a hectare), seasonally waterlogged valleys at the head of a drainage basin where water makes its way to larger channels. Water collected from the runoff of higher ground and channels support the many gardens growing in these valleys. Dambos can maintain water during prolonged droughts, and have been the only farms to produce maize during some droughts.
A more comprehensive approach to reducing all agricultural inputs, from water to fertilizer, is to adopt the lessons of permaculture. This is a sustainable agricultural system based on observing natural systems and working with, rather than against, nature. It integrates animal husbandry, energy–efficiency, and water harvesting and conservation techniques. It emphasizes growing a variety of crops which offer different benefits and soil management. Plants and animals are grown for their fertilizer or because they produce natural pesticides; plant and animal waste is composted and put back in the soil. Pests such as snails are "harvested" to feed livestock such as ducks and geese, and the land is contoured to catch rainwater and mulched to reduce evaporation. Multipurpose use of the land helps makes the system stronger against floods, fires, and pests.
Permaculture’s particular practices can vary from place to place, based on observation on what works for that climate, soil and cultural setting.
New Sources for Water and energy
Although demand management should always be examined first when additional power or water is needed, conservation will not always preclude the need for new sources of supply. There are many sustainable ways to get power or water which cause less damage to ecosystems and communities than the large–scale infrastructure projects currently in favor with planners. Not all options can truly serve as "alternatives" to large infrastructure projects because their capacity is substantially smaller. Large–scale projects are not always the most appropriate option, however – but this needs to be evaluated in the context of nationwide and regional planning for energy development and catchment management. In addition, some of the systems described below already have or are beginning to have large–scale application – wind power, for example. Here are some ideas worth exploring.
Water Groundwater Replenishment
Groundwater currently makes up a large part of the water supply of many Southern African countries. While some countries appear to have plentiful groundwater resources, others recognize that in some cases their water supply aquifers are being rapidly depleted. Because of the region’s erratic rainfall pattern, it is not uncommon for water managers to temporarily over–extract water from certain aquifers to make it through dry periods, and allow aquifers to recharge during wetter years. But longterm over–pumping of groundwater can cause the water table to drop (up to hundreds of metres), or allow salty water to be move into the water table, making it unpotable or causing land subsidence. Usually aquifers will recover if allowed to rest and recharge, but they can compress when water is removed and never regain their previous storage capacity.
Namibia has been studying the possibility of using aquifers as underground reservoirs to stretch existing surface supplies. By artificially injecting certain aquifers with purified surface water to be extracted later, the Windhoek municipality hopes to reduce the amount of water lost each year to evaporation. The city estimates that it could save more than 10 percent of its water supply using this method.
In India, two–thirds of the villages in Gujarat now have no permanent, reliable source of water, mainly because of the over–exploitation of groundwater. To help solve the problem, villagers are building small earthen impoundments across seasonal streams to create a small pond during the monsoon, which is used to recharge groundwater supplies. After the monsoon, the pond gradually recedes. The impoundments are only used to restore the groundwater, and are never tapped directly for water supply. The technology is very simple, relatively cheap to build, and easy to maintain. A government–funded group helps villagers design and pay for the impoundments. Villagers are responsible for building and maintaining their impoundments, and about 20 percent of the building costs. One Indian engineer believes such projects could ultimately collect up to 50 percent of the water that falls on the state.
Groundwater dams provide another way to replenish groundwater. These are underground water barriers which trap groundwater in a certain area and prevent it from flowing away underground. In some areas the groundwater table has fallen so dramatically that even a good rainfall will not raise the water table. By collecting rainwater in these underground reservoirs, the water table in some places has risen from a depth of 200 feet to 20 feet. People in India’s deserts have been using this kind of technology for centuries, and now this practice has been introduced to the hillsides as well. The head of one village stated, "Dried wells now hold water round the year".;
In Africa and elsewhere around the world, more communities are returning to small–scale water harvesting, often using a system that collects water from house rooftops. A January 19, 1999 article in the Ethiopian newspaper The Monitor describes a successful roof water harvesting programme begun by the Ministry of Agriculture with help from the Swedish International Development Agency (SIDA) and a local NGO called Water Action. "This new introduction can enable households to save water that they can use for drinking purposes for up to five months, and with an average size reservoir. Such households might even have some extra water to spare for garden plants".; The only issue for most Ethiopians, the article notes, is the cost. The water tank, water conduit system and gutter cost more than most farmers can afford. It is hoped that the programme will get wider usage with the help of subsidies through international aid agencies, and research efforts to bring down the cost of the materials.
A South African group, Association for Water and Rural Development (AWARD – see Contacts), has created an information sheet on how to collect water from the roof of a house, school or other building. The group calculates that for every 30mm of rain falling, a house with a 50–square–metre roof designed to funnel it into a water tank could collect 1200 litres. AWARD estimates that this could save a person 16 trips to the local water–collection source. The group estimates tank costs at anywhere from R180 for a 2500 litre concrete block tank to R1000 for a 4500 litre steel tank purchased from a manufacturer.
Some 70 percent of the earth’s surface is water, but most of that is undrinkable seawater. By volume, only 3 percent of all water on earth is fresh water, and only about 1 percent is easily accessible surface freshwater. Water desalination is a process used to remove salt and other dissolved solids from brackish or salt water to create fresh water.
Desalination is an attractive water source for many reasons, especially because the supply is virtually limitless and unaffected by drought. For coastal countries, desalted water is not vulnerable to political changes, unlike water supply from shared rivers. For landlocked countries, piping water from the coast involves additional costs and cooperation. Desalting technologies can be built in stages to meet demand, unlike most large–scale water infrastructure projects. Desalination projects also do not lead to the displacement of indigenous peoples, changed agricultural lifestyles or serious ecological impacts.
Desalting processes are mainly used to convert salty water into drinkable water. It is also used to clean up agricultural drainage and industrial waste water contaminated with nitrates, pesticides and organic matter; to improve the quality of drinking water that is high in dissolved minerals; for municipal waste water treatment; and to improve taste, odor and color of drinking water.
In most cases, desalted water is not the sole source of a community’s water supply – though this may change as the cost of desalted water goes down (and especially for coastal areas that are very short of water). It is usually combined with water from less expensive sources. In 1991, desalting plants in approximately 120 countries worldwide had the capacity to produce 15.54 billion litres a day. In many areas of the Caribbean, North Africa and the Middle East, desalted water is used as the main source of municipal supply. At this time, Saudi Arabia ranks first in total capacity with about 24 percent of the world’s capacity.
The most common concerns about desalination are that the process is too expensive and consumes too much energy. In some places, desalinized water costs many times more than conventional local water sources (on Namibia’s dry northern coast, for example, water from a new desalination plant is expected to cost 35 percent more than local groundwater). However, technical breakthroughs are beginning to lower the price (although still not to the artificially low levels that the agriculture industry is used to paying for water). Cost comparisons for desalted water are often made to existing water supplies, which generally did not include a full, fair cost–benefit analysis when they were developed. To be fair, comparisons should be made to the cost of developing other new sources (and all costs should be included in the analysis, such as environmental and social costs). Given that scenario, desalting may be found to be financially and environmentally competitive with building dams, aqueducts and other new water infrastructure.
The amount of salt to be removed greatly affects the cost of desalting, as does the method used to remove salts. The more salts to be removed, the more expensive the desalting process. The capacity of the desalting plant also impacts costs, with larger plants generally being more economical. The most significant factor in desalinated water is energy. Energy for most current technologies amounts to about 30–40 percent of the total cost. Other factors include the amount and type of treatment required, treatment process selected, disposal of the removed salts (concentrate), regulatory issues, land costs and conveyance of the water to and from the plant.
There have also been recent breakthroughs that are expected to reduce the costs for desalination, primarily by cutting back how much energy is required. For example, in 1998 the Singapore–based company AquaGen International announced that it has developed a cheaper, portable water desalination plant that can be assembled anywhere quickly. AquaGen International chief Gavin Liau said the modular system of its plant makes installation easy. The unit can produce 100 cubic metres (25,000 gallons) of water for less than US$300,000. Liau said AquaGen sells two types of desalination plants – one that uses steam and the other with electricity to generate the heat needed to extract the salt. The company says that both types are up to three times more energy efficient than those now in use. The plants are relatively small, producing up to 5,000 cubic metres of drinking water per day compared to up to 327,000 cubic metres/day for the big plants in the Middle East. AquaGen is doing a feasibility study for a large–scale plant that can process 45,000 cubic metres and hoped would be operational in four years.
Israeli, Palestinian and US scientists are embarking on an ambitious desalination programme that is intended to create a "New Desalinized Middle East", according to one of the scientists working on the project. One of the programme’s goals is to build solar–powered desalination machines that can fit on a truck, then teach villagers to use them and even make them. The programme will also look at how water is affected by salt and pollutants. According to World Water & Environmental Engineering (January 1999), it began work in July 1998, in conjunction with the US Department of Energy and US Environmental Protection Agency. A larger solar–powered desalination unit is undergoing testing now. The fully self–supporting desalination system was being evaluated in early 1999 by Al–Azhar University in Gaza, Palestine, and the Japanese company Ebara. The system can desalinate up to 600 litres of brackish water a day. The system is being designed with irrigation in mind, and the company plans to develop micro–irrigation systems in parallel. The company also plans to develop larger–scale units, although the advantage of the smaller scale one is its portability and ease of installation. The units require little maintenance, as they have few moving parts.
New developments in alternative energy may prove to be a boost for desalination as well. Solar thermal power and fuel cells (both of which are described in this section) may provide good sources of power for desalination plants. Since places with good solar power potential are usually the places most in need of water, there is a huge potential to link the two.
A largely untapped source of water for irrigation and groundwater recharge is treated municipal wastewater. Recycling a "waste" product into a reliable water supply has huge benefits. Recycling wastewater makes use of the nutrients in sewage to feed crops and keeps them from polluting waterways. It postpones the need to enlarge and update costly new sewage discharge systems, and eliminates the problems from discharging wastewater into rivers and oceans. It protects freshwater ecosystems by reducing the amount of water extracted from rivers and lakes. Recycled wastewater can also be used to help restore aquatic ecosystems harmed from over–extraction. Using recycled wastewater instead of importing water from hundreds of kilometres away can also result in significant energy savings.
Israel has the most advanced system of wastewater recycling. Currently, 70 percent of sewage is treated and used for irrigation. Officials predict that by 2010, one–fifth of the nation’s total water supply will come from recycled wastewater. Israel uses many different treatment schemes for its many water–reuse projects. One method relies on algae–activated organisms to treat the wastwater. The wastewater is initially stored in a series of ponds in which the anaerobic and aerobic treatment is sufficient to irrigate crops.
Calcutta, India, channels much of its raw sewage into a system of natural lagoons, where fish are raised. The city’s 3,000 hectares of lagoons produce about 6,000 metric tons of fish a year for urban consumers. The fish are safe to eat because the complex biological interactions in the lagoons remove harmful pathogens from the sewage.
As the technology to treat wastewater has improved, so have the applications for the use of the water. A small but growing number of cities are beginning to use highly treated wastewater to supplement drinking water supplies.
Highly treated wastewater cannot be piped directly into a water supply. Most commonly, wastewater is used to augment the drinking–water supply by adding it first to a lake, reservoir, or underground aquifer. The mixture of natural and reclaimed water is then subjected to normal water treatment before it is distributed as drinking water for the community.
A 1998 report by the US–based National Research Council notes that governments and water managers must not take shortcuts in planning to use wastewater. Before deciding to add reclaimed wastewater to urban water supplies, they must first fully assess health impacts from likely contaminants and develop comprehensive systems for monitoring, testing, and treatment. Reclaimed water may contain sources of contamination that cannot be determined through current testing or treatment processes.
There is also much water to be gained by reducing that used for sewage treatment. Treating waste is a hugely water–intensive process, and the commonly used systems cannot be sustainably expanded to serve the three billion people now without access to sewage treatment. Natural water treatment systems such as using wetlands often can be an alternative to modern water treatment technologies. Recycling waste for agricultural purposes by using oxidation ponds and aerated lagoons does not require as much land as is often assumed; however, the land requirement of oxidation ponds is a stumbling block for their use – particularly in urban areas. Moreover, it decreases pollution, reduces the need for fertilizers, and often can be accomplished with small–scale, low–cost technology that is based on local traditions, is decentralized and ecologically sound.
New Energy Generation
Solar power is now the world’s second fastest–growing energy source, increasing on average 16 percent per year since 1990. Each year the earth’s surface receives about 10 times as much energy from sunlight as is contained in all the known reserves of coal, oil, natural gas and uranium combined, according to Scientific American magazine. Using just 1 percent of the earth’s deserts to produce solar energy would provide more energy than is currently being produced worldwide by fossil fuels, say industry analysts. While solar has its limitations, it is especially appropriate for off–grid applications, where most of the world’s 330 million families (2 billion people) without power live. Still, production of PV units (not to mention the money to purchase them) lags behind need.
There are a number of ways to convert energy from the sun. The two most common are photovoltaic cells (PV), and solar thermal. Solar thermal has more potential as a large–scale energy source, while PVs are excellent for powering buildings off the energy grid.
PVs work by converting the sun’s light energy into direct–current electricity. PVs have no moving parts and use no fuel. The price for PVs have dropped more than 100 fold in the past 25 years, as their use has grown. Already, new technologies are lowering the cost of manufacturing solar cells. Scientists believe that such technologies can cut solar cell costs from $4,000 per kilowatt in 1998 to $1,000 in the next decade, which would make them a competitive source of electricity in many parts of the world.
PVs have many advantages:
According to the WorldWatch Institute, approximately 500,000 homes around the world are now generating their own power with PVs. For the more than 2 billion people not connected to a grid, solar power could be the most affordable way to get energy.
In the US and elsewhere, some utilities have set up "net metering" systems, which allow grid–connected homeowners who have installed solar systems to feed solar energy back into the grid system. Feeding in their own solar power makes the homeowner’s electricity meter run backwards, thereby reducing the household’s energy bill accordingly. At the end of the month, if the consumer has used more energy than their solar system generated, they owe the utility the difference; if they generated more electricity than they used, the utility owes them. No special metering equipment is required. This system encourages the installation of solar systems because homeowners get advantages even if they are not home to use the power they are generating. Currently, 20 states in the United States have such programmes.
Larger scale solar power systems can be used to replace a utility’s outdated or highly polluting energy plants. Solar thermal systems generate heat by using lenses and reflectors to concentrate the sun’s energy. Because the heat can be stored, these plants can provide power around the clock. Prototypes have been developed that can provide large–scale power generation. A US programme, ReCast, is working to create "Solar enterprise zones" to encourage this kind of technology around the world. The group says that these plants should be producing 700 megawatts by the year 2003, and 5,000 MW by 2010. As the volume in this technology increases, prices will go down.
Wind power is in the short term one of the most promising renewable energy sources. Technological advances have caused the price of wind power in favourable locations to drop dramatically. According to the American Wind Energy Association, the global wind–energy industry set a record for new installed generating capacity in 1997. The rate of growth appeared likely to maintain wind’s position as one of the world’s fastest growing energy sources. Although wind power cannot produce power 100 percent of the time and therefore cannot be relied upon for all of a country’s power (just as hydropower cannot, due to droughts), it could provide a much greater proportion of energy production in places with good winds.
If wind power is to become a major electricity producer, wind farms must be developed in such a way that they benefit the communities in which they are installed. Denmark is perhaps one of the best examples of this. It began its wind power programme from the "bottom up", and Danish communities were made shareholders in windfarm co–ops. Denmark now leads the world in its wind power capabilities.
Egypt is in the pilot stage of a programme whose goal is for the nation to become Africa’s Number 1 wind–power generator. Egypt’s Red Sea coastline is one of the world’s best sites for wind power potential. In places, winds average 23 miles per hour for 95 percent of the year (the biggest wind power farms in Europe and the US average 16 mph winds). The 43 percent greater wind speed found in Egypt delivers almost 300 percent as much power. The power from these excellent winds is also cheap: at one new site, windmills are expected to generate power at a cost of 4 cents per kilowatt hour, or one–third the average cost in Germany. Wind farms are being built in a 32–square–mile area of desert set aside by the government near Zafarana. By the end of the year 2000, the farms should be generating 90 megawatts (enough to power a town of 15,000). Egypt’s renewable energy authority hopes the farms will generate 600 megawatts by 2005, which is about three percent of the country’s current needs.
A fuel cell produces energy electrochemically, without combustion, by harnessing the reaction of hydrogen and oxygen to produce electricity, water and heat – and almost no pollution. A fuel cell works like a battery but, unlike a battery, it does not run down or require recharging. It will produce energy as long as fuel is supplied. Natural gas or other fuels can be used if the fuel cell has a reformer to convert the fuel to hydrogen. Fuel cells are a very efficient form of energy production.
Fuel cells can be used to power vehicles, individual buildings and large–scale utilities. They offer a very decentralized form of power production, since they can be put to use as needed at individual buildings or at local power plants, making long–range transmission wires unnecessary. The technology has the potential to have a big impact in reducing worldwide greenhouse emissions: for example, 10,000 fuel–cell vehicles running on non–petroleum fuel would reduce oil consumption by 6.98 million gallons per year. Fuel–cell cars are expected to be widely available by 2003 or even sooner. Fuel cell automobiles offer the advantages of battery–powered (electric) vehicles but can be refueled more quickly and go longer between refuelings. A recent study by General Motors noted that fuel cell car engines could be built for about the same price as an internal combustion engine.
Fuel cells can also be used to take advantage of methane and carbon dioxide emissions produced by wastewater treatment facilities. The US has a number of fuel cell installations at wastewater treatment plants, which not only produce electric power and heat for the community but also eliminate the pollution produced as a by–product of wastewater treatment.
Fuel cells can promote energy diversity and a transition to renewable energy sources. A variety of fuels – hydrogen, methanol, ethanol, natural gas, and liquefied petroleum gas – can be used. Energy also could be supplied by biomass, wind and solar energy.
In some areas, small–scale hydropower schemes may be the most appropriate energy source. When carefully planned and implemented, small dams (under 10 megawatts) can be less harmful to the environment and surrounding communities than large dams. Small projects can also better serve the local economy, and help develop local skills and resources. However, scale alone does not determine whether a project will be socially or environmentally harmful. As with planning any hydro–
power project, small dams should be evaluated individually for their impacts on the catchment and communities, and for their fit in an overall catchment management plan. (See Beyond Big Dams, IRN 1997)
Geothermal energy is derived from the earth’s core. It is the same source from which volcanoes and earthquakes get their energy. In some places, natural hot "reservoirs" below the surface of the earth provide large–scale sources of geothermal power. In 1993, these natural steam sources accounted for 9 percent of Kenya’s energy supply, 28 percent of Nicaragua’s power and 26 percent of the Philippines, to name a few nations that are making use of their geothermal reserves.
Geothermal reserves are not needed to take advantage of geothermal power on a small scale, however. Any place on earth can take advantage of geothermal heat–pump technology, which capitalizes on the stable temperature below the earth’s surface. This uses heat–pump technology to extract heat from the earth in winter for heating buildings and to dissipate heat in summer for cooling. While the temperature of the soil to several feet below the surface varies with the seasons, below that depth the earth’s temperature stays about the same year–round. This technology has made significant advances in the past few years. Installation costs have been reduced by 30 percent compared to earlier designs.
The use of biological waste to generate energy has been proven to be a practical and economical means of recycling large volumes of organic wastes. Waste from domestic, agricultural, commercial and industrial sources is digested by microorganisms, which produces a mixture of methane and carbon dioxide, which is then turned into energy. Methane is non–toxic, smokeless and flammable. One cubic metre of biogas produces enough fuel to cook three meals for a family of five to six people, running one 60–watt electric light up to seven hours, or running a one–horse–power internal combustion engine for two hours.
Biogas technology has a number of benefits. It can digest human waste and decrease the spread of disease from pathogens in the waste, including organisms that cause infections such as typhoid, Guinea worm, cholera, dysentery, hookworm and bilharzia.
In many developing countries, most organic wastes such as dung and agricultural residue are burned directly for fuel (referred to as "biomass" energy production). The combustion of these wastes often creates air pollution and causes respiratory diseases. According to the World Health Organization (1992), 700 million women in developing countries are at risk for developing serious health problems from the burning of biomass. These problems would be reduced if a portion of these wastes were used in a biogas process.
Creating energy from ocean waves may never become a major source for power, but it continues to become more economically and technically viable. According to New Scientist magazine (May 16, 1998), the average cost of wave power is now 10 times lower than it was in 1982. The magazine reports that three of the six wave–power devices now available can produce power that is economically competitive, and one device produces power that is one–third cheaper than coal in the UK. New Scientist reports that the British government is now seriously considering including wave power as part of its goal to reduce carbon emissions by 10 percent by the year 2010.
Another experimental energy source is being researched in the US island of Hawaii, Japan, Bali and elsewhere. The technology uses the difference in temperature between ocean surface water and water up to 1,000 metres deep to create energy.